I just watched my bees swarm. They're clustered in a lilac bush right outside the hive. I just put a super on yesterday after I watched what might have been an attempted swarm (I watched it closely but it never turned into a cluster anywhere). Now this. I'm wondering if it happened because of weather? I read that prolonged periods of bad weather can cause a swarm, and we've definitely had that. Overcast, cold, and rainy for a days. Yesterday was the first day of sun in a couple weeks, and now we're back to crappy weather.
So, anyway, I read somewhere you can put bees back in their hive if you correct the conditions that caused swarming. I don't know for sure what caused it, but I think weather is a reasonable guess -- they're otherwise doing really well in that hive, and I think they have enough ventilation.
P.S. We were just packing up to go fishing when this happened. Nice timing, bees!:mad: